Metadata-based endorsement

ABSTRACT

An example operation may include one or more of executing, by an endorser node, a smart contract to generate a blockchain transaction data, generating, by the endorser node, metadata specific to the endorser node, concatenating, by the endorser node, the metadata with the blockchain transaction data, signing, by the endorser node, a concatenation result data with a key of the endorser node, and providing, by the endorser node, the signed concatenation result data to a committer node for verification.

TECHNICAL FIELD

This application generally relates to a database storage system, andmore particularly, to metadata-based endorsement.

BACKGROUND

A centralized database stores and maintains data in one single database(e.g., database server) at one location. This location is often acentral computer, for example, a desktop central processing unit (CPU),a server CPU, or a mainframe computer. Information stored on acentralized database is typically accessible from multiple differentpoints. Multiple users or client workstations can work simultaneously onthe centralized database, for example, based on a client/serverconfiguration. A centralized database is easy to manage, maintain, andcontrol, especially for purposes of security because of its singlelocation. Within a centralized database, data redundancy is minimized asa single storing place of all data also implies that a given set of dataonly has one primary record.

However, a centralized database suffers from significant drawbacks. Forexample, a centralized database has a single point of failure. Inparticular, if there are no fault-tolerance considerations and ahardware failure occur (for example, the hardware, a firmware, and/or asoftware failure), all data within the database is lost and work of allusers is interrupted. In addition, centralized databases are highlydependent on network connectivity. As a result, the slower theconnection, the amount of time needed for each database access isincreased. Another drawback is the occurrence of bottlenecks when acentralized database experiences high traffic due to a single location.Furthermore, a centralized database provides limited access to databecause only one copy of the data is maintained by the database. As aresult, multiple devices cannot access the same piece of data at thesame time without creating significant problems or risk overwritingstored data. Furthermore, because a database storage system has minimalto no data redundancy, data that is unexpectedly lost is very difficultto retrieve other than through manual operation from back-up storage.

Conventionally, a centralized database is limited by low searchcapability, lack of security and slow speed of transactions. As such,what is needed is a blockchain-based solution to overcome thesesignificant drawbacks.

Currently, blockchain implementations produce transactions composed bydata agreed upon during the consensus phase. However, there aresituations where data that is not agreed upon is required to be added tothe transactions. For example, every blockchain node may keep track ofthe time involved in the execution of the transaction or thenode-specific costs incurred during the execution of the transaction andthis data should be appended to the blockchain transaction in such a waythat every blockchain participant is clear about it. In other words,endorsers have to agree on exactly the same transaction result. However,it is not possible to settle data specific to each of the endorsers inthe ledger.

Accordingly, it is desired to enable an endorser node to settleendorser-specific data (e.g., resources, errors, times, costs, etc.) tobe utilized during an endorsement of a transaction.

SUMMARY

One example embodiment provides a system that includes a processor andmemory, wherein the processor is configured to perform one or more ofexecute a smart contract to generate a blockchain transaction data,generate metadata specific to the endorser node, concatenate themetadata with the blockchain transaction data, sign a concatenationresult data with a key of the endorser node, and provide the signedconcatenation result data to a committer node for verification.

Another example embodiment provides a method that includes one or moreof executing, by an endorser node, a smart contract to generate ablockchain transaction data, generating, by the endorser node, metadataspecific to the endorser node, concatenating, by the endorser node, themetadata with the blockchain transaction data, signing, by the endorsernode, a concatenation result data with a key of the endorser node, andproviding, by the endorser node, the signed concatenation result data toa committer node for verification.

A further example embodiment provides a non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of executing a smart contract togenerate a blockchain transaction data, generating metadata specific tothe endorser node, concatenating the metadata with the blockchaintransaction data, signing a concatenation result data with a key of theendorser node, and providing the signed concatenation result data to acommitter node for verification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a network diagram of a system including a ledgerdatabase, according to example embodiments.

FIG. 2A illustrates an example peer node configuration, according toexample embodiments.

FIG. 2B illustrates a further peer node configuration, according toexample embodiments.

FIG. 3 illustrates a permissioned network, according to exampleembodiments.

FIG. 4A illustrates a flow diagram, according to example embodiments.

FIG. 4B illustrates a further flow diagram, according to exampleembodiments.

FIG. 5A illustrates an example system configured to perform one or moreoperations described herein, according to example embodiments.

FIG. 5B illustrates a further example system configured to perform oneor more operations described herein, according to example embodiments.

FIG. 5C illustrates a smart contract configuration among contractingparties and a mediating server configured to enforce the smart contractterms on the blockchain according to example embodiments.

FIG. 5D illustrates another additional example system, according toexample embodiments.

FIG. 6A illustrates a process of new data being added to a database,according to example embodiments.

FIG. 6B illustrates contents a data block including the new data,according to example embodiments.

FIG. 7 illustrates an example system that supports one or more of theexample embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined in any suitable manner inone or more embodiments. For example, the usage of the phrases “exampleembodiments”, “some embodiments”, or other similar language, throughoutthis specification refers to the fact that a particular feature,structure, or characteristic described in connection with the embodimentmay be included in at least one embodiment. Thus, appearances of thephrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof network data, such as, packet, frame, datagram, etc. The term“message” also includes packet, frame, datagram, and any equivalentsthereof. Furthermore, while certain types of messages and signaling maybe depicted in exemplary embodiments they are not limited to a certaintype of message, and the application is not limited to a certain type ofsignaling.

Example embodiments provide methods, systems, components, non-transitorycomputer readable media, devices, and/or networks, which provide forendorsement of transactions based on an endorser-specific metadata inblockchain networks.

A decentralized database is a distributed storage system which includesmultiple nodes that communicate with each other. A blockchain is anexample of a decentralized database which includes an append-onlyimmutable data structure resembling a distributed ledger capable ofmaintaining records between mutually untrusted parties. The untrustedparties are referred to herein as peers or peer nodes. Each peermaintains a copy of the database records and no single peer can modifythe database records without a consensus being reached among thedistributed peers. For example, the peers may execute a consensusprotocol to validate blockchain storage transactions, group the storagetransactions into blocks, and build a hash chain over the blocks. Thisprocess forms the ledger by ordering the storage transactions, as isnecessary, for consistency. In a public or permission-less blockchain,anyone can participate without a specific identity. Public blockchainsoften involve native crypto-currency and use consensus based on variousprotocols such as Proof of Work (PoW). On the other hand, a permissionedblockchain database provides a system which can secure inter-actionsamong a group of entities which share a common goal, but which do notfully trust one another, such as businesses that exchange funds, goods,information, and the like.

A blockchain operates arbitrary, programmable logic, tailored to adecentralized storage scheme and referred to as “smart contracts” or“chaincodes.” In some cases, specialized chaincodes may exist formanagement functions and parameters which are referred to as systemchaincode. Smart contracts are trusted distributed applications whichleverage tamper-proof properties of the blockchain database and anunderlying agreement between nodes which is referred to as anendorsement or endorsement policy. In general, blockchain transactionstypically must be “endorsed” before being committed to the blockchainwhile transactions which are not endorsed are disregarded. A typicalendorsement policy allows chaincode to specify endorsers for atransaction in the form of a set of peer nodes that are necessary forendorsement. When a client sends the transaction to the peers specifiedin the endorsement policy, the transaction is executed to validate thetransaction. After validation, the transactions enter an ordering phasein which a consensus protocol is used to produce an ordered sequence ofendorsed transactions grouped into blocks.

Nodes are the communication entities of the blockchain system. A “node”may perform a logical function in the sense that multiple nodes ofdifferent types can run on the same physical server. Nodes are groupedin trust domains and are associated with logical entities that controlthem in various ways. Nodes may include different types, such as aclient or submitting-client node which submits a transaction-invocationto an endorser (e.g., peer), and broadcasts transaction-proposals to anordering service (e.g., ordering node). Another type of node is a peernode which can receive client submitted transactions, commit thetransactions and maintain a state and a copy of the ledger of blockchaintransactions. Peers can also have the role of an endorser, although itis not a requirement. An ordering-service-node or orderer is a noderunning the communication service for all nodes, and which implements adelivery guarantee, such as a broadcast to each of the peer nodes in thesystem when committing transactions and modifying a world state of theblockchain, which is another name for the initial blockchain transactionwhich normally includes control and setup information.

A ledger is a sequenced, tamper-resistant record of all statetransitions of a blockchain. State transitions may result from chaincodeinvocations (i.e., transactions) submitted by participating parties(e.g., client nodes, ordering nodes, endorser nodes, peer nodes, etc.).A transaction may result in a set of asset key-value pairs beingcommitted to the ledger as one or more operands, such as creates,updates, deletes, and the like. The ledger includes a blockchain (alsoreferred to as a chain), which is used to store an immutable, sequencedrecord in blocks. The ledger also includes a state database whichmaintains a current state of the blockchain. There is typically oneledger per channel. Each peer node maintains a copy of the ledger foreach channel of which they are a member.

A chain is a transaction log which is structured as hash-linked blocks,and each block contains a sequence of N transactions where N is equal toor greater than one. The block header includes a hash of the block'stransactions, as well as a hash of the prior block's header. In thisway, all transactions on the ledger may be sequenced andcryptographically linked together. Accordingly, it is not possible totamper with the ledger data without breaking the hash links. A hash of amost recently added blockchain block represents every transaction on thechain that has come before it, making it possible to ensure that allpeer nodes are in a consistent and trusted state. The chain may bestored on a peer node file system (i.e., local, attached storage, cloud,etc.), efficiently supporting the append-only nature of the blockchainworkload.

The current state of the immutable ledger represents the latest valuesfor all keys that are included in the chain transaction log. Because thecurrent state represents the latest key values known to a channel, it issometimes referred to as a world state. Chaincode invocations executetransactions against the current state data of the ledger. To make thesechaincode interactions efficient, the latest values of the keys may bestored in a state database. The state database may be simply an indexedview into the chain's transaction log, it can therefore be regeneratedfrom the chain at any time. The state database may automatically berecovered (or generated if needed) upon peer node startup, and beforetransactions are accepted.

Some benefits of the instant solutions described and depicted hereininclude a method and system for endorsement of transactions based on anendorser-specific metadata in blockchain networks. The exemplaryembodiments solve the issues of time and trust by extending features ofa database such as immutability, digital signatures and being a singlesource of truth. The exemplary embodiments provide a solution forendorsement of transactions based on an endorser-specific metadata inblockchain-based network. The blockchain networks may be homogenousbased on the asset type and rules that govern the assets based on thesmart contracts.

Blockchain is different from a traditional database in that blockchainis not a central storage, but rather a decentralized, immutable, andsecure storage, where nodes must share in changes to records in thestorage. Some properties that are inherent in blockchain and which helpimplement the blockchain include, but are not limited to, an immutableledger, smart contracts, security, privacy, decentralization, consensus,endorsement, accessibility, and the like, which are further describedherein. According to various aspects, the system for endorsement oftransactions based on an endorser-specific metadata in blockchainnetworks is implemented due to immutable accountability, security,privacy, permitted decentralization, availability of smart contracts,endorsements and accessibility that are inherent and unique toblockchain. In particular, the blockchain ledger data is immutable andthat provides for efficient method for endorsement of transactions basedon an endorser-specific metadata in blockchain networks. Also, use ofthe encryption in the blockchain provides security and builds trust. Thesmart contract manages the state of the asset to complete thelife-cycle. The example blockchains are permission decentralized. Thus,each end user may have its own ledger copy to access. Multipleorganizations (and peers) may be on-boarded on the blockchain network.The key organizations may serve as endorsing peers to validate the smartcontract execution results, read-set and write-set. In other words, theblockchain inherent features provide for efficient implementation of amethod for endorsement of transactions based on an endorser-specificmetadata.

One of the benefits of the example embodiments is that it improves thefunctionality of a computing system by implementing a method forendorsement of transactions based on an endorser-specific metadata inblockchain-based systems. Through the blockchain system describedherein, a computing system can perform functionality for endorsement oftransactions based on an endorser-specific metadata in blockchainnetworks by providing access to capabilities such as distributed ledger,peers, encryption technologies, MSP, event handling, etc. Also, theblockchain enables to create a business network and make any users ororganizations to on-board for participation. As such, the blockchain isnot just a database. The blockchain comes with capabilities to create aBusiness Network of users and on-board/off-board organizations tocollaborate and execute service processes in the form of smartcontracts.

The example embodiments provide numerous benefits over a traditionaldatabase. For example, through the blockchain the embodiments providefor immutable accountability, security, privacy, permitteddecentralization, availability of smart contracts, endorsements andaccessibility that are inherent and unique to the blockchain.

Meanwhile, a traditional database could not be used to implement theexample embodiments because it does not bring all parties on thebusiness network, it does not create trusted collaboration and does notprovide for an efficient storage of digital assets. The traditionaldatabase does not provide for a tamper proof storage and does notprovide for preservation of the digital assets being stored. Thus, theproposed method for endorsement of transactions based on anendorser-specific metadata in blockchain networks cannot be implementedin the traditional database.

Meanwhile, if a traditional database were to be used to implement theexample embodiments, the example embodiments would have suffered fromunnecessary drawbacks such as search capability, lack of security andslow speed of transactions. Additionally, the automated method forendorsement of transactions based on an endorser-specific metadata inthe blockchain network would simply not be possible.

Accordingly, the example embodiments provide for a specific solution toa problem in the arts/field of endorsement of transactions in theblockchain networks.

The example embodiments also change how data may be stored within ablock structure of the blockchain. For example, a digital asset data maybe securely stored within a certain portion of the data block (i.e.,within header, data segment, or metadata). By storing the digital assetdata within data blocks of a blockchain, the digital asset data may beappended to an immutable blockchain ledger through a hash-linked chainof blocks. In some embodiments, the data block may be different than atraditional data block by having a personal data associated with thedigital asset not stored together with the assets within a traditionalblock structure of a blockchain. By removing the personal dataassociated with the digital asset, the blockchain can provide thebenefit of anonymity based on immutable accountability and security.

According to the exemplary embodiments, a method and system for addingof not agreed upon metadata during an execution of a transaction isprovided. The metadata may be specific for each of the blockchain (BC)nodes that prepare the transaction. In one embodiment, the metadata maybe added to the blockchain transaction. After the execution of thetransaction, each BC node may sign both the transaction data produced bythe smart-contract and the metadata that is specific to the BC node.Thus, each of the BC nodes may produce a settlement for the entire dataproduced by this node.

According to the exemplary embodiments, the not agreed upon data (i.e.,node-specific metadata) may be used for analytics about what the nodehas executed, how many attempts (or how long) the BC node takes toexecute a transaction, etc. In one embodiment, the BC node-specificcosts may be included in the metadata. These data fields of the metadatamay be used at a later phase for billing purposes. Also, the BCnode-specific data may include communication media between endorser BCnodes and committer BC nodes. For example, an endorser BC node maydetect anomalies during the execution of the smart contract and mayregister the anomalies into the metadata. According to one embodiment,custom metadata attached to a transaction is generated for each BC nodeexecuting the smart contract.

In one exemplary embodiment, a configuration file may be used to specifyto the endorser BC node which metadata should be attached to theendorsed transaction (e.g., CPU time, memory usage and time used duringthe endorsement of the transaction, etc.). The smart contract may havelogic to place data items into the metadata. The underlying language andplatform to write the smart contract may need to be extended so theendorser BC node could incorporate metadata into the endorsement, butnot as a part of the transaction result that must be agreed upon betweenall of the endorser nodes of the transaction.

According to the exemplary embodiments, the endorsement with themetadata is implemented as follows. During an execution of a smartcontract, each endorser BC node may produce a signature of thetransaction. This signature is a non-repudiable property that specifiesthe result obtained by the node, as well as the metadata attached to it.According to the exemplary embodiments, two possible approaches toendorsement of the transaction and the metadata may be used. Once theendorser BC node has executed the transaction, the endorser BC node mayadd two signatures, the first signature for the transaction result andthe second signature for the attached metadata. Alternatively, the BCnode may concatenate the transaction result with the metadata producedby the BC node. Then, the BC node may sign the concatenation resultantdata. During the verification phase, the result and the particularmetadata for every BC node must be composed to verify the node'ssignature. The metadata may be encrypted in such a way that onlydesignated recipients may interpret (i.e., decrypt) the metadata. Thecombination of an endorser identity and endorser metadata may be signedby a key of the endorser node. The committer BC nodes may still verifythe endorsing policy as follows. For each endorsement, the committer BCnode may validate the signature, using a hash(digestOfCommonEndorsement+metadata_(i)), where the metadata, representsa digestOfIndividualMetadata.

According to one exemplary embodiment, the concatenation of the twohashes may be signed: first hash of a transaction result (e.g.ReadWriteset) and a second hash of metadata generated by the endorserpeer. Thus, the endorsed transaction includes the ReadWriteset and themetadata of each endorser together with their signature(s).

The committer BC node may calculate a digest of a transaction (Tx)payload (smart contract+input parameters+readWrite-set+ . . . ). Foreach endorsement:

-   -   The committer BC node may calculate a digest of the        concatenation result of the digest of the Tx payload with the        metadata;    -   The committer BC node may verify the endorser's signature        against the digest of the concatenation of the digest of the Tx        payload with the metadata. The committer BC node may verify that        valid endorsements fulfill endorsing policy of the smart        contract. This procedure ensures that the endorsers had agreed        on the same transaction result while the individual metadata of        the endorsers is also verified.

FIG. 1 illustrates a logic network diagram for adding endorser-specificmetadata to a transaction in a blockchain network, according to exampleembodiments.

Referring to FIG. 1 , the example network 100 includes an endorser node102 connected to committer node(s) 105. The endorser node 102 may beconnected to a blockchain 106 that has a ledger 108 for storingtransactions (Tx) 110. While this example describes in detail only oneendorser node 102, multiple such nodes may be connected to theblockchain 106. It should be understood that the endorser node 102 mayinclude additional components and that some of the components describedherein may be removed and/or modified without departing from a scope ofthe endorser node 102 disclosed herein. The endorser node 102 may be acomputing device or a server computer, or the like, and may include aprocessor 104, which may be a semiconductor-based microprocessor, acentral processing unit (CPU), an application specific integratedcircuit (ASIC), a field-programmable gate array (FPGA), and/or anotherhardware device. Although a single processor 104 is depicted, it shouldbe understood that the endorser node 102 may include multipleprocessors, multiple cores, or the like, without departing from thescope of the endorser node 102 system.

The endorser node 102 may also include a non-transitory computerreadable medium 112 that may have stored thereon machine-readableinstructions executable by the processor 104. Examples of themachine-readable instructions are shown as 114-122 and are furtherdiscussed below. Examples of the non-transitory computer readable medium112 may include an electronic, magnetic, optical, or other physicalstorage device that contains or stores executable instructions. Forexample, the non-transitory computer readable medium 112 may be a RandomAccess memory (RAM), an Electrically Erasable Programmable Read-OnlyMemory (EEPROM), a hard disk, an optical disc, or other type of storagedevice.

The processor 104 may fetch, decode, and execute the machine-readableinstructions 114 to execute a smart contract to generate a blockchaintransaction data. As discussed above, the blockchain ledger 108 maystore transactions 110. The blockchain 106 network may be configured touse one or more smart contracts that manage transactions for multipleparticipating nodes. The endorser node 102 may provide signedtransactions and metadata to the committer node(s) 105.

The processor 104 may fetch, decode, and execute the machine-readableinstructions 116 to generate metadata specific to the endorser node 102.The processor 104 may fetch, decode, and execute the machine-readableinstructions 118 to concatenate the metadata with the blockchaintransaction data. The processor 104 may fetch, decode, and execute themachine-readable instructions 120 to sign a concatenation result datawith a key of the endorser node. The processor 104 may fetch, decode,and execute the machine-readable instructions 122 to provide the signedconcatenation result data to a committer node 105 for verification.

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these four nodes are depicted by example only).These nodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions based onendorsement policy and may provide an ordering service for allblockchain nodes in the architecture 200. A blockchain node may initiatea blockchain authentication and seek to write to a blockchain immutableledger stored in blockchain layer 216, a copy of which may also bestored on the underpinning physical infrastructure 214. The blockchainconfiguration may include one or more applications 224 which are linkedto application programming interfaces (APIs) 222 to access and executestored program/application code 220 (e.g., chaincode, smart contracts,etc.) which can be created according to a customized configurationsought by participants and can maintain their own state, control theirown assets, and receive external information. This can be deployed as atransaction and installed, via appending to the distributed ledger, onall blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, the smartcontract logic 226 may be processed by one or more processing entities(e.g., virtual machines) included in the blockchain layer 216. Theresult 228 may include data blocks reflecting endorsed transactions. Thephysical infrastructure 214 may be utilized to retrieve any of the dataor information described herein.

Within chaincode, a smart contract may be created via a high-levelapplication and programming language, and then written to a block in theblockchain. The smart contract may include executable code which isregistered, stored, and/or replicated with a blockchain (e.g.,distributed network of blockchain peers). A transaction is an executionof the smart contract code which can be performed in response toconditions associated with the smart contract being satisfied. Theexecuting of the smart contract may trigger a trusted modification(s) toa state of a digital blockchain ledger. The modification(s) to theblockchain ledger caused by the smart contract execution may beautomatically replicated throughout the distributed network ofblockchain peers through one or more consensus protocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto the blockchain. The code may be used to create a temporary datastructure in a virtual machine or other computing platform. Data writtento the blockchain can be public and/or can be encrypted and maintainedas private. The temporary data that is used/generated by the smartcontract is held in memory by the supplied execution environment andthen deleted once the data needed for the blockchain is identified.

A chaincode may include the code interpretation of a smart contract,with additional features. As described herein, the chaincode may beprogram code deployed on a computing network, where it is executed andvalidated by chain validators together during a consensus process. Thechaincode receives a hash and retrieves from the blockchain a hashassociated with the data template created by use of a previously storedfeature extractor. If the hashes of the hash identifier and the hashcreated from the stored identifier template data match, then thechaincode sends an authorization key to the requested service. Thechaincode may write to the blockchain data associated with thecryptographic details. In FIG. 2A, addition of endorser-specificmetadata may include execution of the smart contract. One function maybe to commit a transaction related to execution of the smart contract onthe ledger for recording transaction data, which may be provided to oneor more of the nodes 204-210.

FIG. 2B illustrates an example of a transactional flow 250 between nodesof the blockchain in accordance with an example embodiment. Referring toFIG. 2B, the transaction flow may include a transaction proposal 291sent by an application client node 260 to an endorsing peer node 281.The endorsing peer 281 may verify the client signature and execute achaincode function to initiate the transaction. The output may includethe chaincode results, a set of key/value versions that were read in thechaincode (read set), and the set of keys/values that were written inchaincode (write set). The proposal response 292 is sent back to theclient 260 along with an endorsement signature, if approved. The client260 assembles the endorsements into a transaction payload 293 andbroadcasts it to an ordering service node 284. The ordering service node284 then delivers ordered transactions as blocks to all peers 281-283 ona channel. Before committal to the blockchain, each peer 281-283 mayvalidate the transaction. For example, the peers may check theendorsement policy to ensure that the correct allotment of the specifiedpeers have signed the results and authenticated the signatures againstthe transaction payload 293.

Referring again to FIG. 2B, the client node 260 initiates thetransaction 291 by constructing and sending a request to the peer node281, which is an endorser. The client 260 may include an applicationleveraging a supported software development kit (SDK), such as NODE,JAVA, PYTHON, and the like, which utilizes an available API to generatea transaction proposal. The proposal is a request to invoke a chaincodefunction so that data can be read and/or written to the ledger (i.e.,write new key value pairs for the assets). The SDK may serve as a shimto package the transaction proposal into a properly architected format(e.g., protocol buffer over a remote procedure call (RPC)) and take theclient's cryptographic credentials to produce a unique signature for thetransaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies theendorsing peers' signatures and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction and broadcasts the transaction proposaland response within a transaction message to the ordering node 284. Thetransaction may contain the read/write sets, the endorsing peers'signatures and a channel ID. The ordering node 284 does not need toinspect the entire content of a transaction in order to perform itsoperation. Instead, the ordering node 284 may simply receivetransactions from all channels in the network, order themchronologically by channel, and create blocks of transactions perchannel.

The blocks of the transaction are delivered from the ordering node 284to all peer nodes 281-283 on the channel. The transactions 294 withinthe block are validated to ensure any endorsement policy is fulfilledand to ensure that there have been no changes to ledger state for readset variables since the read set was generated by the transactionexecution. Transactions in the block are tagged as being valid orinvalid. Furthermore, in step 295 each peer node 281-283 appends theblock to the channel's chain, and for each valid transaction the writesets are committed to current state database. An event is emitted, tonotify the client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

FIG. 3 illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture,and a certificate authority 318 managing user roles and permissions. Inthis example, the blockchain user 302 may submit a transaction to thepermissioned blockchain network 310. In this example, the transactioncan be a deploy, invoke or query, and may be issued through aclient-side application leveraging an SDK, directly through a REST API,or the like. Trusted business networks may provide access to regulatorsystems 314, such as auditors (the Securities and Exchange Commission ina U.S. equities market, for example). Meanwhile, a blockchain networkoperator system of nodes 308 manages member permissions, such asenrolling the regulator system 310 as an “auditor” and the blockchainuser 302 as a “client.” An auditor could be restricted only to queryingthe ledger whereas a client could be authorized to deploy, invoke, andquery certain types of chaincode.

A blockchain developer system 316 writes chaincode and client-sideapplications. The blockchain developer system 316 can deploy chaincodedirectly to the network through a REST interface. To include credentialsfrom a traditional data source 330 in chaincode, the developer system316 could use an out-of-band connection to access the data. In thisexample, the blockchain user 302 connects to the network through a peernode 312. Before proceeding with any transactions, the peer node 312retrieves the user's enrollment and transaction certificates from thecertificate authority 318. In some cases, blockchain users must possessthese digital certificates in order to transact on the permissionedblockchain network 310. Meanwhile, a user attempting to drive chaincodemay be required to verify their credentials on the traditional datasource 330. To confirm the user's authorization, chaincode can use anout-of-band connection to this data through a traditional processingplatform 320.

FIG. 4A illustrates a flow diagram 400 of an example method of addingendorser specific metadata to a transaction in blockchain networks,according to example embodiments. Referring to FIG. 4A, the method 400may include one or more of the steps described below.

FIG. 4A illustrates a flow chart of an example method executed by theendorser node 102 (see FIG. 1 ). It should be understood that method 400depicted in FIG. 4A may include additional operations and that some ofthe operations described therein may be removed and/or modified withoutdeparting from the scope of the method 400. The description of themethod 400 is also made with reference to the features depicted in FIG.1 for purposes of illustration. Particularly, the processor 104 of theendorser node 102 may execute some or all of the operations included inthe method 400.

With reference to FIG. 4A, at block 412, the processor 104 may execute asmart contract to generate a blockchain transaction data. At block 414,the processor 104 may generate metadata specific to the endorser node.At block 416, the processor 104 may concatenate the metadata with theblockchain transaction data. At block 418, the processor 104 may sign aconcatenation result data with a key of the endorser node. At block 420,the processor 104 may provide the signed concatenation result data to acommitter node for verification.

FIG. 4B illustrates a flow diagram 450 of an example method of addingmetadata to transactions in a blockchain network, according to exampleembodiments. Referring to FIG. 4B, the method 450 may also include oneor more of the following steps. At block 452, the processor 104 maygenerate a signature of the blockchain transaction data and a signatureof the metadata. At block 454, the processor 104 may provide a signedblockchain transaction data and a signed metadata to the committer nodefor verification. At block 456, the processor 104 may encrypt themetadata for decryption by a designated recipient. At block 458, theprocessor 104 may generate the metadata during an execution of ablockchain transaction. At block 460, the processor 104 may generate themetadata based on a configuration file. At block 462, the processor 104may generate the metadata by an execution of a smart contract logic.

FIG. 5A illustrates an example system 500 that includes a physicalinfrastructure 510 configured to perform various operations according toexample embodiments. Referring to FIG. 5A, the physical infrastructure510 includes a module 512 and a module 514. The module 514 includes ablockchain 520 and a smart contract 530 (which may reside on theblockchain 520), that may execute any of the operational steps 508 (inmodule 512) included in any of the example embodiments. Thesteps/operations 508 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 530 and/orblockchains 520. The physical infrastructure 510, the module 512, andthe module 514 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 512and the module 514 may be a same module.

FIG. 5B illustrates an example system 540 configured to perform variousoperations according to example embodiments. Referring to FIG. 5B, thesystem 540 includes a module 512 and a module 514. The module 514includes a blockchain 520 and a smart contract 530 (which may reside onthe blockchain 520), that may execute any of the operational steps 508(in module 512) included in any of the example embodiments. Thesteps/operations 508 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 530 and/orblockchains 520. The physical infrastructure 510, the module 512, andthe module 514 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 512and the module 514 may be a same module.

FIG. 5C illustrates an example smart contract configuration amongcontracting parties and a mediating server configured to enforce thesmart contract terms on the blockchain according to example embodiments.Referring to FIG. 5C, the configuration 550 may represent acommunication session, an asset transfer session or a process orprocedure that is driven by a smart contract 530 which explicitlyidentifies one or more user devices 552 and/or 556. The execution,operations and results of the smart contract execution may be managed bya server 554. Content of the smart contract 530 may require digitalsignatures by one or more of the entities 552 and 556 which are partiesto the smart contract transaction. The results of the smart contractexecution may be written to a blockchain 520 as a blockchaintransaction. The smart contract 530 resides on the blockchain 520 whichmay reside on one or more computers, servers, processors, memories,and/or wireless communication devices.

FIG. 5D illustrates a common interface 560 for accessing logic and dataof a blockchain, according to example embodiments. Referring to theexample of FIG. 5D, an application programming interface (API) gateway562 provides a common interface for accessing blockchain logic (e.g.,smart contract 530 or other chaincode) and data (e.g., distributedledger, etc.) In this example, the API gateway 562 is a common interfacefor performing transactions (invoke, queries, etc.) on the blockchain byconnecting one or more entities 552 and 556 to a blockchain peer (i.e.,server 554). Here, the server 554 is a blockchain network peer componentthat holds a copy of the world state and a distributed ledger allowingclients 552 and 556 to query data on the world state as well as submittransactions into the blockchain network where, depending on the smartcontract 530 and endorsement policy, endorsing peers will run the smartcontracts 530.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.For example, FIG. 6 illustrates an example computer system architecture600, which may represent or be integrated in any of the above-describedcomponents, etc.

FIG. 6A illustrates a process 600 of a new block being added to adistributed ledger 630, according to example embodiments, and FIG. 6Billustrates contents of a block structure 650 for blockchain, accordingto example embodiments. Referring to FIG. 6A, clients (not shown) maysubmit transactions to blockchain nodes 621, 622, and/or 623. Clientsmay be instructions received from any source to enact activity on theblockchain 630. As an example, clients may be applications that act onbehalf of a requester, such as a device, person or entity to proposetransactions for the blockchain. The plurality of blockchain peers(e.g., blockchain nodes 621, 622, and 623) may maintain a state of theblockchain network and a copy of the distributed ledger 630. Differenttypes of blockchain nodes/peers may be present in the blockchain networkincluding endorsing peers which simulate and endorse transactionsproposed by clients and committing peers which verify endorsements,validate transactions, and commit transactions to the distributed ledger630. In this example, the blockchain nodes 621, 622, and 623 may performthe role of endorser node, committer node, or both.

The distributed ledger 630 includes a blockchain 632 which storesimmutable, sequenced records in blocks, and a state database 634(current world state) maintaining a current state of the blockchain 632.One distributed ledger 630 may exist per channel and each peer maintainsits own copy of the distributed ledger 630 for each channel of whichthey are a member. The blockchain 632 is a transaction log, structuredas hash-linked blocks where each block contains a sequence of Ntransactions. Blocks may include various components such as shown inFIG. 6B. The linking of the blocks (shown by arrows in FIG. 6A) may begenerated by adding a hash of a prior block's header within a blockheader of a current block. In this way, all transactions on theblockchain 632 are sequenced and cryptographically linked togetherpreventing tampering with blockchain data without breaking the hashlinks. Furthermore, because of the links, the latest block in theblockchain 632 represents every transaction that has come before it. Theblockchain 632 may be stored on a peer file system (local or attachedstorage), which supports an append-only blockchain workload.

The current state of the blockchain 632 and the distributed ledger 632may be stored in the state database 634. Here, the current state datarepresents the latest values for all keys ever included in the chaintransaction log of the blockchain 632. Chaincode invocations executetransactions against the current state in the state database 634. Tomake these chaincode interactions extremely efficient, the latest valuesof all keys are stored in the state database 634. The state database 634may include an indexed view into the transaction log of the blockchain632, it can therefore be regenerated from the chain at any time. Thestate database 634 may automatically get recovered (or generated ifneeded) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse thetransaction based on simulated results. Endorsing nodes hold smartcontracts which simulate the transaction proposals. When an endorsingnode endorses a transaction, the endorsing node creates a transactionendorsement which is a signed response from the endorsing node to theclient application indicating the endorsement of the simulatedtransaction. The method of endorsing a transaction depends on anendorsement policy which may be specified within chaincode. An exampleof an endorsement policy is “the majority of endorsing peers mustendorse the transaction.” Different channels may have differentendorsement policies. Endorsed transactions are forwarded by the clientapplication to ordering service 610.

The ordering service 610 accepts endorsed transactions, orders them intoa block, and delivers the blocks to the committing peers. For example,the ordering service 610 may initiate a new block when a threshold oftransactions has been reached, a timer times out, or another condition.In the example of FIG. 6A, blockchain node 622 is a committing peer thathas received a new data block 650 for storage on blockchain 630.

The ordering service 610 may be made up of a cluster of orderers. Theordering service 610 does not process transactions, smart contracts, ormaintain the shared ledger. Rather, the ordering service 610 may acceptthe endorsed transactions and specifies the order in which thosetransactions are committed to the distributed ledger 630. Thearchitecture of the blockchain network may be designed such that thespecific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.)becomes a pluggable component.

Transactions are written to the distributed ledger 630 in a consistentorder. The order of transactions is established to ensure that theupdates to the state database 634 are valid when they are committed tothe network. Unlike a crypto-currency blockchain system (e.g., Bitcoin,etc.) where ordering occurs through the solving of a cryptographicpuzzle, or mining, in this example the parties of the distributed ledger630 may choose the ordering mechanism that best suits that network.

When the ordering service 610 initializes a new block 650, the new block650 may be broadcast to committing peers (e.g., blockchain nodes 621,622, and 623). In response, each committing peer validates thetransaction within the new block 650 by checking to make sure that theread set and the write set still match the current world state in thestate database 634. Specifically, the committing peer can determinewhether the read data that existed when the endorsers simulated thetransaction is identical to the current world state in the statedatabase 634. When the committing peer validates the transaction, thetransaction is written to the blockchain 632 on the distributed ledger630, and the state database 634 is updated with the write data from theread-write set. If a transaction fails, that is, if the committing peerfinds that the read-write set does not match the current world state inthe state database 634, the transaction ordered into a block will stillbe included in that block, but it will be marked as invalid, and thestate database 634 will not be updated.

Referring to FIG. 6B, a block 650 (also referred to as a data block)that is stored on the blockchain 632 of the distributed ledger 630 mayinclude multiple data segments such as a block header 660, block data670, and block metadata 680. It should be appreciated that the variousdepicted blocks and their contents, such as block 650 and its contents.Shown in FIG. 6B are merely for purposes of example and are not meant tolimit the scope of the example embodiments. In some cases, both theblock header 660 and the block metadata 680 may be smaller than theblock data 670 which stores transaction data, however, this is not arequirement. The block 650 may store transactional information of Ntransactions (e.g., 100, 500, 1000, 2000, 3000, etc.) within the blockdata 670. The block 650 may also include a link to a previous block(e.g., on the blockchain 632 in FIG. 6A) within the block header 660. Inparticular, the block header 660 may include a hash of a previousblock's header. The block header 660 may also include a unique blocknumber, a hash of the block data 670 of the current block 650, and thelike. The block number of the block 650 may be unique and assigned in anincremental/sequential order starting from zero. The first block in theblockchain may be referred to as a genesis block which includesinformation about the blockchain, its members, the data stored therein,etc.

The block data 670 may store transactional information of eachtransaction that is recorded within the block 650. For example, thetransaction data may include one or more of a type of the transaction, aversion, a timestamp, a channel ID of the distributed ledger 630, atransaction ID, an epoch, a payload visibility, a chaincode path (deploytx), a chaincode name, a chaincode version, input (chaincode andfunctions), a client (creator) identify such as a public key andcertificate, a signature of the client, identities of endorsers,endorser signatures, a proposal hash, chaincode events, response status,namespace, a read set (list of key and version read by the transaction,etc.), a write set (list of key and value, etc.), a start key, an endkey, a list of keys, a Merkel tree query summary, and the like. Thetransaction data may be stored for each of the N transactions.

In some embodiments, the block data 670 may also store data 672 whichadds additional information to the hash-linked chain of blocks in theblockchain 632. Accordingly, the data 672 can be stored in an immutablelog of blocks on the distributed ledger 630. Some of the benefits ofstoring such data 672 are reflected in the various embodiments disclosedand depicted herein.

The block metadata 680 may store multiple fields of metadata (e.g., as abyte array, etc.). Metadata fields may include signature on blockcreation, a reference to a last configuration block, a transactionfilter identifying valid and invalid transactions within the block, lastoffset persisted of an ordering service that ordered the block, and thelike. The signature, the last configuration block, and the orderermetadata may be added by the ordering service 610. Meanwhile, acommitter of the block (such as blockchain node 622) may addvalidity/invalidity information based on an endorsement policy,verification of read/write sets, and the like. The transaction filtermay include a byte array of a size equal to the number of transactionsin the block data 670 and a validation code identifying whether atransaction was valid/invalid.

FIG. 7 is not intended to suggest any limitation as to the scope of useor functionality of embodiments of the application described herein.Regardless, the computing node 700 is capable of being implementedand/or performing any of the functionality set forth hereinabove.

In computing node 700 there is a computer system/server 702, which isoperational with numerous other general purposes or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 702 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 702 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 702 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 7 , computer system/server 702 in cloud computing node700 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 702 may include, but are notlimited to, one or more processors or processing units 704, a systemmemory 706, and a bus that couples various system components includingsystem memory 706 to processor 704.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 702 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 702, and it includes both volatileand non-volatile media, removable and non-removable media. System memory706, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 706 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)710 and/or cache memory 712. Computer system/server 702 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 714 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 806 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 716, having a set (at least one) of program modules 718,may be stored in memory 706 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 718 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 702 may also communicate with one or moreexternal devices 720 such as a keyboard, a pointing device, a display722, etc.; one or more devices that enable a user to interact withcomputer system/server 702; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 702 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 724. Still yet, computer system/server 702 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 726. As depicted, network adapter 726communicates with the other components of computer system/server 702 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 702. Examples include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, recipient or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a Smart phoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms, etc.) thereto.

What is claimed is:
 1. A system comprising: an endorser node of ablockchain network, the endorser node comprising: a processor that whenexecuting one or more instructions stored in a memory is configured to:endorse a transaction to generate an endorsed transaction comprising,transaction data; generate a plurality of metadata specific to theendorser node, specify certain metadata, of the plurality of metadata,to be concatenated with the endorsed transaction, wherein the certainmetadata is not part of the endorsed transaction, concatenate thecertain metadata with the transaction data to generate a concatenationresult data, and sign the concatenation result data with a key of theendorser node; and a committer node of the blockchain network, thecommitter node comprising: a processor that when executing one or moreinstructions stored in a memory is configured to: receive the signedconcatenation result data from the endorser node, calculate a digest ofthe concatenation result data, and verify the endorsed transaction basedon the key of the endorser matching the digest of the concatenationresult data.
 2. The system of claim 1, wherein the processor is furtherconfigured to: encrypt the metadata for decryption by a designatedrecipient.
 3. The system of claim 1, wherein, when the processor isconfigured to generate the metadata, the processor is further configuredto: generate the metadata during an execution of the blockchaintransaction.
 4. The system of claim 1, wherein, when the processor isconfigured to generate the metadata, the processor is further configuredto: generate the metadata based on a configuration file.
 5. The systemof claim 1, wherein, when the processor is configured to generate themetadata, the processor is further configured to: generate the metadatabased on the smart contract.
 6. A method, comprising: endorsing, by anendorser node of a blockchain network, a comprising transaction datatransaction comprising transaction data; generating, by the endorsernode, a plurality of metadata specific to the endorser node; specifying,by the endorser node, certain metadata, of the plurality of metadata, tobe concatenated with the endorsed transaction, wherein the certainmetadata is not part of the endorsed transaction; concatenating, by theendorser node, the certain metadata with the blockchain transaction datato generate a concatenation result data; signing, by the endorser node,the concatenation result data with a key of the endorser node;receiving, by a committer node of the blockchain network, the signedconcatenation result data from the endorser node; calculating, by thecommitter node, a digest of the concatenation result data; andverifying, by the committer node, the endorsed transaction based on thekey of the endorser matching the digest of the concatenation resultdata.
 7. The method of claim 6, further comprising: encrypting themetadata for decryption by a designated recipient.
 8. The method ofclaim 6, wherein the generating the metadata further comprises:generating the metadata during the blockchain transaction.
 9. The methodof claim 6, wherein the generating the metadata further comprises:generating the metadata based on a configuration file.
 10. The method ofclaim 6, wherein the generating the metadata further comprises:generating the metadata by an execution of the smart contract.
 11. Anon-transitory computer readable medium comprising one or moreinstructions that when executed by a processor cause the processor toperform: endorsing, by an endorser node of a blockchain network, acomprising transaction data transaction comprising transaction data;generating, by the endorser node, a plurality of metadata specific tothe endorser node; specifying, by the endorser node, certain metadata,of the plurality of metadata, to be concatenated with the endorsedtransaction, wherein the certain metadata is not part of the endorsedtransaction; concatenating, by the endorser node, the certain metadatawith the blockchain transaction data to generate a concatenation resultdata; signing, by the endorser node, the concatenation result data witha key of the endorser node; receiving, by a committer node of theblockchain network, the signed concatenation result data from theendorser node; calculating, by the committer node, a digest of theconcatenation result data; and verifying, by the committer node, theendorsed transaction based on the key of the endorser matching thedigest of the concatenation result data.
 12. The non-transitory computerreadable medium of claim 11, wherein the one or more instructionsfurther cause the processor to perform: encrypting the metadata fordecryption by a designated recipient.
 13. The non-transitory computerreadable medium of claim 11, wherein the generating the metadata furthercomprises: generating the metadata based on a configuration file. 14.The non-transitory computer readable medium of claim 11, wherein thegenerating the metadata further comprises: generating the metadata by anexecution of the smart contract.